I am getting very similar results to those reported by @shanerock with at least one recent image downloaded from beagleboard.org different from the one he is using. It looks to me as if the uboot version(s) which are being put into these images are more recent than the build of uboot from 2019 which I get when I allow the device to boot from the eMMC, and these builds have the behaviour of outputting the “Trying to boot from MMC1” line directly after startup, and then chaining to partition 1 in the eMMC for the boot process instead of chaining to the filesystem on the SD card.
@shanerock’s log reports that the U-Boot build is
U-Boot 2022.04-ge0d31da5 (Aug 04 2023 - 18:48:26 +0000)
On the image I am running at the moment, the report has the same prefix “U-Boot 2022.04-ge0d31da5” but has a timestamp of “Dec 07 2023 - 16:17:19 +0000”.
I have multiple images available to run here downloaded from different parts of beableboard.org, the names and SHA256’s of the downloadable xz files are as follows:
tim@tim-OptiPlex-7450-AIO:~/Downloads/RPi+BBB$ sha256sum *.img.xz
58e76be5fd7415cca89f1187c6d96ed697b8d77fd2739ab4978f2d0ba9c87641 am335x-debian-11.7-iot-armhf-2023-09-02-4gb.img.xz
62ee9f6dab49d6df8b0822e5b5a491a34d92643d0b166392de0b5d0eb5bcf9f9 am335x-debian-11.8-iot-armhf-2023-10-07-4gb.img.xz
3fdac493ab7074ef8d5258abf07a1bdff1afdd2fda88f6b4625a015f003f4687 am335x-debian-11.8-minimal-armhf-2023-10-07-2gb.img.xz
8363a991d6115cf5906408f9875badc99fe38452436605af1906edbbc8dc0d36 am335x-debian-11.8-xfce-armhf-2023-10-07-4gb.img.xz
d66e120d2055cf4b9f30109488f293ff7b38a7b39c7374c1a163cce7a946c13d am335x-debian-12.4-minimal-armhf-2024-01-06-2gb.img.xz
a61b749119ce0a9827e2f5e0e36831a0b139482798fac668337b6da6fcea7038 am335x-eMMC-flasher-debian-11.7-xfce-armhf-2023-09-02-4gb.img.xz
f0ee00a83a72abb09a74663f8b860ab1c3fc0f5fd4ea29202057c7c93892f27e am335x-eMMC-flasher-debian-11.8-iot-armhf-2023-10-07-4gb.img.xz
I think the image in the device at the moment is am335x-debian-12.4-minimal-armhf-2024-01-06-2gb.img.xz (given the dates on the others it is unlikely they would contain a U-Boot binary built in December 2023). I’ll work through all of these again and report back if I find any which work, or which fail with different symptoms.
If there is a specific build anyon on the forum would suggest I try (particularly if there are any builds with U-boot built from different git commits, as I’m guessing @shanerock and I have builds based on the same commit).